Electric plug in decade resistance unit



Feb. 23, 1954 R. v. BVAUM Erm. 2,670,422 ELECTRIC PLUG IN DECADE Rzswmcsuurr Filed Sept. 15. 1952 2 Shuts-Sheet l llHIllllIlllllfllIllllllllllIllllllllllllllllllllllillllllllllllll\ I .32

INVENTORS Richard V. Baum bar/es D. Harri/ll- BY Irving 3. OsofskyATTORNEY 0 III/i R. V. BAUM ET AL ELECTRIC PLUG IN DECADE RESISTANCEUNIT Filed Sept. 15, 1952 Feb. 23, 1954 2 Sheets-Shbt 2 z. a z.

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BY Irv/'05 B. Osofsk ATTORNEY Patented Feb. 23, 1954 ELEGTRIG PLUG INDECADERESISTANGE' UNIT Richard V. Baum, Akron, Charles. D. Morrill,

Cnyahogat Balls and Irving B. Osofsky, Akron..

0liio, assignors to. Goodyear Aircraft Corporation', Akron, Ohio acorporation of Delaware Application September 15,1952,,Serialfio..309,7.1'6*

7' Claims.

This invention relates to at variable electric decade resistanceunit andin particular. to a glue-in variable resistance device; capable ofconveniently-- selecting within: its range andwith:- out: the: use of ameasuring device, a desired resistance value.

Heretofore; devices have been known using a plurality. of: decadeswitches for" selecting for an electricrcircuitithe requiredresistance;However, such; devices could notv be-set with an accuracy required forcertain purposes because the stop values? obtainable; by a decade switchare fixed and: are not adjustable for values therebetween. Besides,vthese instruments are too bulky and: in many cases can.- not beiusedbecause of lack of space. Another disadvantage is their more com,-plicated construction. and high cost.,

It'is the generalobject ofv the invention tea-void andovercome theforegoing. and other difficulties or. and objections to prior: artpractices by; the provision of making the deviceas simple and ascompactzas possible: at greatest. accuracy for obtaining a desiredresistance value Another object of the invention is the possi bility:of: assembling all armature parts of the device outside its housing andto mount them in assembled operable" condition in. the housing withoutany additional fastening; except by closingthe-housing;

Another object of the: invention is the provie sion; for connecting thedevice; with an electric conductor by" the: plug-in? system.

A further object of the; invention is to reduce the device to a. sizewhich permits large; numbers'of them: to be installed'iinasmall-spaceofan apparatus;

Aestillsfuuther object of therinventi'onaiszto make setting; andireading; of: the resistance: values easy:

The aforesaid. objects of: the invention, and other: objects which willbecome apparent aszthe description proceedsare achieved by-mounting inan: oblong; cylindrical; split housing: and longitu dinall'y; thereofin: consecutive order and with compactness the operating parts: ofthedevice consisting" ot, a resistor assembly; a plurality of decadeswitches: and a" rheostat, one: end of; the housing being provided:with: a; jack; and its other end? with a plug; All armatureapartsofthedevice: may be fully assembled: and tested: outm'de the housing to:be readily insertabl'e' therein; for use. Thisccylindrica'l and compactconstruction makes-z possible to install" the device with greatest easeand large numbers, as; for insinncetin an, electroniccomputer, within avery smaitapacezbyraz simple plug in process. Without the. use ofameasuringdevice :anyresistancevalue within the range OfithiSJlll-litcan be obtainediwith an accuracy of approximately 1 percent, whereaswith the use of a measuring device;. because of the adjustability of:the rheostat anaccuracy of the unit maybe obtainedevenwithinozl per centof its maximum resistance. This device.- can pro,- vide rangesofresistance not available insmall accurate potentiometer-sand'canbemade in sizes of approximately 1% diameter and 3%" in length.

For a better understandingofthe inyentionreierence should be had to theaccompanying'drawineawherein:

Fig. 1-, is a longitudinal crosssectional view taken on line I-I of Fig.2 of one embodiment of the invention with the inside parts shownzinview.

Fig. 2 isasideview of the-device; partly broken away.

Fig. 315 atcross sectionalview taken on; line III-L-IlofiFig. land.

Fig. 4 is an electric circuit diagramof the device.

With specific, reference to the formof. the: in:- vention illustrated.in the drawingsthe numeral I. indicates. in. general acylindrica'lhousing made of plastics which. consists oftwo symmetrical halves-2 and3- enclosing the armature of there sistance; unit. These; halves aresecured together by capbolts 4;=5 and.- 6: and nuts 1 and. 8 with thebolt caps and nuts hidden for. smooth appearance insocketsS. and Hi.'I'he housing I contains-a resistorv assembly H, a decade switch t2 forthe selection of high resistances, a second decade switchifiif'orselectingresistances of only one tenth the-valueof. thoseselected. by switch t2 and a-linear potentiometer orrheostat [4 forselecting resistances of one tenth of the: valueof thoseselectedbyswitch Is; allindicated as a whoie respectively.

The: resistor assembly H7 iscomposed of. retainer plate: I 5.;insertedina groove [6 0i the-housing- I: and: provided at one side? with: spacedthin metalilayers; l of suitableconfiguration. 0n the retainer piate 15'are. mounted on a circie; and; parallel with the'housing axis, precisionresistors iliizten in number; the wires'ofwhich pass through the-piateIS and are soldered to the: metal layers Hf. A; spider-like separatorl9; made of plastic slipped. intospaces between the resistors 18 toinsulate them; keeps the resistor" H3 properly spacedcfromeaoh other:Fiveoftheresistors t8,

fourofwhieh' have a resistance of I R, and the remaining one of S R, arewired to the decade The decade switch 42 consists of a switch plate,

20, made of plastics, held in a groove 2| and is provided, showndiagrammatically in Fig. 4, with thin metal layers forming spot contacts22 placed in a half circle and opposite thereof two spaced quadrantcontacts 23 and 24 on which rides the switch contactor 25 fastened tothe knurled thumb wheel 26 of frusto-conical shape provided with indexnumbers to 9, corresponding to the R-' values obtainable from the groupof four 1 R and one R resistors. The thumb wheel 26, made of plasticsand being integral with its shaft 21, is journaled in bearings 23 and 29placed in. the transverse portions 39 and Si in the housing halves 2 and3. The axis of the bearings 28 and 29 is spaced from and parallel to thelongitudinal axis of easing I so that for turning the wheel 26 it passesthrough a slot 32 and partially extends with its circumference beyondthe circumference of the housing I. The side of the thumb wheel '26opposite the contacts 22, 23 and 2:3 is provided with dimples 33corresponding with the number of spot contacts 22. The dimples 33 areengaged by a protuberance 34 on a fiat spring 35 seated in a slot 36 inthe transverse portion 3% to provide sensory indexing.

The decade switch is mounted on the same axis as decade switch 12 is ofsubstantially the same construction and, therefore, does not requireseparate description.

Having also its axis common with that of the decade switches 12 and i3,the linear potentiometer I4 of standard type having a wiper arm 3'!turning about the center of the rheostat resistance 38 and in contacttherewith is operated by the thumb wheel 39 fixed to the shaft 49 by ascrew M and indexed by numbers 1 to 12 for resistances of one tenth thevalue of those obtained by the decade switch it and which is wired to ajack 42 inserted at one end of the resistance unit, whereas, its otherend is provided a plug 43 wired to the resistance assembly H.

A pin 44 of the housing secures the resistance unit against turning inplugged-in position if desirable.

' As shown in Fig. 1, the entire armature of the device can becompletely assembled and tested outside its housing and readily insertedtherein without requiring special fastening means, since the boltsholding the housing halves 2 and 3 together also keep all parts enclosedtherein in proper place.

The circuit diagram, Fig. 4, of the plug-in resistance unit clearlyshows the wiring of this unit with all switches in zero position. Byturning the thumb wheel 26 of decade switch H. in the direction of thearrow the four resistors 1 R are consecutively added to each other to a4 R resistance with the contactor 25 sliding along the quadrant contact24. By further turning the thumb wheel 25 the contactor 25 disengagesthe i R resistors and passes the current over the spot contact 5 andquadrant contact 23 through resistor 5 R. Because the spot contactsnumbered 0 to d are connected by jumper wires 45 with the spot contactsnumbered i-to 9, respectively, further turning of thumb wheel-26 addsagain the 1R resistors to the 5 R resistor up to a resistance of 9 R.The decade switch IS in series with decade switch i2 is connected in thesame way to the remaining five resistors, four of which having aresistance of 0.1 R each and the other one a resistance of 0.5 R andcontrol resistances between 0 R and 0.9 R. However, because of the fixedspot contacts, no resistance value which is less than one tenth R can beadded or subtracted by the decade switch 13. In order to accomplish thisthe linear potentiometer I4 indexed for one hundredths of R from 0 R to0.12 without fixed stops has been added. Thus, it is possible to set theresistance unit without the use of a measuring instrument within anaccuracy of one hundredth R which is the accuracy of the resistors it,however, by using a measuring instrument an accuracy within onethousandth R is obtainable.

In many cases and especially for electronic computers in which a largenumber of small variable resistance units are needed and must be placedwithin a small space the invention is of particular value. From thedescription it will be recognized that the aforementioned objects of theinvention have been fully achieved, which provides a plug-in resistanceunit of greatest compactness for obtaining resistance values within verysmall limits of accuracy, of small size and weight, of easy assembly atleast labor and low cost. Besides, the resistance values can be combinedand read easier from the thumb wheels which are arranged in line, oneabove the other and close together. Although, the drawings illustrate adecade resistance unit for only two decade switches, a unit for agreater number of decades may be employed.

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent to thoseskilled in this art that various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

What is claimed:

1. A variable electric plug-in decade resistance unit comprising anelongated cylindrical housing made of plastic material including aprecision resistor assembly, a plurality of decade switches and a linearpotentiometer all wired in series and mounted one above the other withinthe housing, said decade switches and said potentiometer having a commonaxis and each being provided for operation with a thumb wheel extendingat least partially beyond the outer circumference of the housing, andmeans secured in the housing and attached to both ends of the resistancewiring for plugging the unit into an electric circuit.

2. A variable electric plug-in decade resistance unit comprising anelongated cylindrical housing consisting of two symmetrical halvesjoined in a plane passing through the central axis of the housing,transverse bolts for holding said halves together, said housing beingprovided with transverse supports spaced from each other and havingbearing surfaces, a set of armatures comprising an assembly of resistorunits of various resistance values, a decade switch wired to a group ofsaid resistor units of high resistance value, a second decade switchwired to another group of said resistor units having one-tenth theresistance of that of said first group, a linear potentiometer indexedfor one hundredth of the unit resistance of the first group of resistorsand being wired in series with both of said switches and. having acommon axis therewith, and plug-- in means at both ends of the-armature,said re sistor assembly, decade switches, potentiometer and plug-inmeans all assembled and tested outside said housing and fitting intosaid bearing surfaces and being held therebetween in operating positionsolely by said bearing surfaces. 4

3. A variable electric plug-in decade resistance unit comprising anelongated substantially cylindrical housing made of two longitudinalhalves;

said housing halves being provided with transverse supports havingbearing surfaces, transverse bolts for holding said halves together, anda set of a completely assembled operating armature including an assemblyof resistor units having various resistance values and being arranged ina circle, a plurality of thumb wheel-operated decade switches, a linearthumb Wheel-operated potentiometer, and plug-in means, all of whichbeing wired in series, said decade switches and said potentiometer, onedisposed above the other, having a common axis parallel to but spacedfrom the longitudinal housing axis, with all parts of the armature beingembedded and fixed in operating and working order between said bearingsurfaces and with portions of the thumb wheels of the switches andpotentiometer protruding beyond the outer surface of the housing foroperating the thumb wheels.

4. An electric decade resistance unit including substantially ten spotcontacts positioned substantially uniformly through about a half circle,an arcuate contact extending through approximately a third quarter ofthe circle, a second arcuate contact extending through approximate lythe fourth quarter of the circle, all contacts being spaced from eachother, a contactor blade pivotal about the center of the circle andadapted to contact one of the spot contacts at one end and one of thearcuate contacts at its opposite end, a one-unit resistance connectedbetween each of the first five spot contacts, a five-unit resistanceconnected between the arcuate contacts, a jumper wire connecting each ofthe first and the sixth, the second and seventh, the third and theeighth, etc., of the spot contacts, and leads connected to the first ofthe spot and arcuate contacts whereby rotation of the contactor bladeconnects into the leads from zero to nine units of resistance.

5. In an electric decade resistance device comprising two decaderesistance units as described in claim 4, being connected in series, oneof said units having resistances of a value of one tenth of those usedin the other unit, and a linear potentiometer connected in series withsaid units and having a total resistance equal to about one eighth of aresistance connected between the spot contacts of the unit having thesmaller resistance of the two units.

6. In an electric resistance device composed of a plurality of decaderesistance units as described in claim 4, said units being connected inseries and each of said units having a resistance value one decadedifierent from the preceding one.

7. A multiple resistance unit having a plurality of spot contactsdivided into two groups, a pair of arcuate contacts, contact arms movingover any one of a. first group of spot contacts and over one or thearcuate contacts, said contact arms being also movable over any one ofthe second group of spot contacts and over the second arcuate contact,jumper wires connecting the first spot contact of the first group to thefirst spot contact of the second group, the second spot contact of thefirst group to the second spot contact of the second group, etc., aresistor associated with each spot contact of the first group, and amultiple unit resistor equal in units to the number of spot contacts inthe first group and connected between the arcuate contacts.

RICHARD V. BAUM.

CHARLES D. MORRILL. IRVING B. OSOFSKY.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,441,399 Clark Jan. 9, 1923 2,142,355 Hastings Jan. 3, 19392,264,033 Youhouse Nov. 25, 1941 FOREIGN PATENTS Number Country Date534,251 Great Britain Mar. 3, 1941

